The invention relates to a portable light source system incorporating a power conditioning sub-system, used to supply light for use with medical endoscopes, laryngoscopes, other portable medical illumination devices, and industrial boroscopes.
The use of endoscopes has increasingly become important in many fields. For instance, endoscopes are widely used for many medical procedures providing significant advantages such as greatly enhancing a physician""s ability to remotely view a body cavity. Not only have endoscopes been widely utilized for surgical procedures, but have also been utilized for assisting a physician to accurately place medical equipment into a body cavity, such as the placing of a laryngoscope in a trachea. Illumination levels and color temperature of the illuminating light is selected and must be maintained in these applications.
For instance, in a surgical procedure, it is absolutely critical that the physician have enough illuminating light in the cavity being operated on to perform the procedure accurately and in a timely manner. If the illumination level is poor, it is challenging for the physician to perform the procedure mistake-free. Additionally, if the illumination level is poor, this will have the effect of slowing the physician in performing the procedure which in turn will increase the length of time the patient will have to be under anesthesia, which is highly undesirable. Therefore, a selected minimum illumination level must be met and must also be maintained throughout the length of the procedure. It should also be noted that illumination levels are very important in applications where, for instance a medical device is being inserted into a body such as a laryngoscope. Without proper illumination, the physician may have difficulty inserting the laryngoscope properly without causing damage to for instance, the vocal cords.
Not only is it important to maintain the proper illumination level in medical applications, but it is also very important to maintain the proper color temperature of the illuminating light. For instance, in many surgical procedures, the physician must first inspect the area or cavity where a potential procedure is to take place and based upon what he observes, identify structures, and determine how to proceed. Being able to accurately differentiate between one type of tissue and the next based upon the color or look and texture is therefore critical to not only diagnosis, but also in performing the procedure mistake-free. Therefore, the color temperature of the illuminating light must be accurately supplied and maintained throughout the procedure.
Endoscopy is also becoming increasingly important for industrial applications. For instance, boroscopes having self contained light sources are utilized to illuminate and image small pipelines, cavities, and internal workings of machinery. Illumination levels and color temperature of the illuminating light must also be maintained for these applications.
For instance, where a boroscope is utilized for inspecting small pipelines, cavities, and internal workings of machinery, in many applications it is important that detailed images be obtained to determine if the equipment has been compromised or if failure is imminent. Failure to detect defects due to poor illumination levels or difficulty in perceiving the color of what is being observed could have catastrophic results. Therefore, maintaining effective illumination levels and accurate color temperature throughout the entire inspection is very important.
Portable, lightweight endoscopy systems for use in both medical and industrial applications are also increasingly being utilized. Traditionally, light sources for portable endoscopes, laryngoscopes, other portable medical illumination devices, and industrial boroscopes have comprised a light source that is powered by a battery source, and some means for connecting or disconnecting the light source to the battery. However, this simple means of providing a portable power source has some inherent problems that greatly limit its use.
Due to the nature of primary or secondary electrochemical power sources (batteries), discharge characteristics are such that their voltage decreases as the total available energy decreases. For some battery types, this is due to an increase in internal impedance, and for others, a combination of the latter and a general drop in open circuit voltage. For some secondary systems, battery age and use history also cause an increase in internal impedance, which in turn will result in unsatisfactory voltage decreases.
In a voltage versus discharge (use) time plot, the slope of the curve depends on the above, as well as the discharge current. Typically, the slope increases with larger currents. When powering a light source, such as is utilized with endoscopes, laryngoscopes, other portable medical illumination devices, and industrial boroscopes, this decrease in voltage causes the intensity of the light source output to decrease exponentially, and to decrease or shift in light color temperature, for instance, a shift towards the red. This is undesirable and in many instances is unacceptable for medical or technical illumination, given that the intensity and color temperature of the illuminating light are critical to the application.
In addition, when primary batteries are used, especially relatively small batteries for added portability and weight reduction, the quantity and quality of light output may become unacceptable due to a drop in circuit voltage, even though the battery may still have a relatively large amount of power remaining. Therefore, the useable lifespan of primary batteries has been greatly reduced when used to power a light source in these critical applications due to unsatisfactory voltage output.
Therefore, what is desired is a portable light source system such as is utilized with endoscopes, laryngoscopes, other medical devices, and industrial boroscopes, that will supply a light output that will not vary in intensity over the life of the battery.
It is also desired to provide a portable light source system, such as is utilized with endoscopes, laryngoscopes, other medical devices, and industrial boroscopes, that will supply a light output that will not shift in color temperature over the life of the battery.
It is further desired to provide a portable light source system, such as is utilized with endoscopes, laryngoscopes, other medical devices, and industrial boroscopes, that will effectively utilize substantially all the energy stored in the battery as practicable for the use while still maintaining strict output requirements.
It is still further desired to provide a portable light source system, such as is utilized with endoscopes, laryngoscopes, other medical devices, and industrial boroscopes, with a minimized size, while still maintaining strict output requirements.
These objectives are achieved by providing a system configuration in which a light source is connected to the output of a power conditioning circuit, which is in turn, connected to a battery. This configuration provides for a constant voltage level to be delivered to the light source, regardless of variations in battery condition. Providing a constant voltage level to the light source will thereby ensure a constant level of illumination and prevent a shift of the light source color.
The power conditioning circuit will also allow a much larger percentage of the energy stored in the battery to be utilized while still maintaining a determined substantially constant voltage output that will not cause a drop in light intensity or a shift in color. This increase in efficiency will have a positive impact on the xe2x80x9ccost of use.xe2x80x9d The power conditioning circuit may comprise several forms such as, a step-up, step-down, or step-up/down voltage regulator with constant or adaptive output.
The configuration also allows for re-rating of the light source, in this case a tungsten filament bulb, so as to increase efficiency and color temperature of the light source, without causing premature filament burnout. A 10% increase in filament voltage results in approximately a 40% increase in light output, and a desirable higher color temperature, however, it also causes a 70% decrease in filament life. When re-rating a light bulb, this inverse exponential (twelfth power) relationship of filament life to applied voltage requires a tight control of the applied voltage. It is also contemplated that the present invention can further be configured as an adaptive device, to make use of light output feedback to control and stabilize the light source output.
In one advantageous embodiment an apparatus for providing illuminating light of a selected illumination level and color temperature utilized with a portable imaging device is provided comprising a battery, providing electrical power, and a light source. The apparatus further comprises a power conditioning circuit, connecting the battery with the light source and the power conditioning circuit modifies the electrical power based upon a selected threshold parameter representative of a desired illumination level and a desired color temperature of the illuminating light. The apparatus further comprises a portable imaging device, generating an image. Finally the apparatus is provided such that the power conditioning circuit causes the light source to provide illuminating light of an illumination level and a substantially constant color temperature based upon the selected threshold parameter.
In another advantageous embodiment an apparatus for providing illuminating light of a selected illumination level and color temperature utilized with a portable imaging device is provided comprising a battery, providing electrical power, and a light source, having an illumination rating and a color temperature rating. The apparatus also comprises a power conditioning circuit that connects the battery with the light source, and the power conditioning circuit modifies the electrical power to re-rate the light source to, a selected illumination level different from the illumination rating or a selected color temperature different from the color temperature rating.
In still another advantageous embodiment an apparatus for providing illuminating light of a selected illumination level and color temperature utilized with a portable imaging device is provided comprising a battery, providing electrical power, and a light source, having an illumination rating and a color temperature rating. The apparatus also comprises a power conditioning circuit, that connects the battery with the light source, and the power conditioning circuit modifies the electrical power based upon a selected threshold parameter representative of a desired illumination level and a desired color temperature of the illuminating light. The power conditioning circuit also modifies the electrical power to re-rate the light source to, a selected illumination level different from the illumination rating or a selected color temperature different from the color temperature rating. The apparatus further comprises a portable imaging device, generating an image and the power conditioning circuit causes the light source to provide illuminating light of an illumination level and a substantially constant color temperature based upon the selected threshold parameter.
In yet another advantageous embodiment a method is supplied for providing illuminating light of a selected illumination level and color temperature and utilized with a portable imaging device comprising the steps of supplying electrical power with a battery, selecting a light source having an illumination rating and a color temperature rating, and connecting the battery with the light source through a power conditioning circuit. The method further comprises the steps of selecting a threshold parameter representative of a desired illumination level and a desired color temperature of the illuminating light, and modifying the electrical power with the power conditioning circuit based upon the selected threshold parameter. The method further comprises the steps of modifying the electrical power with the power conditioning circuit to re-rate the light source to, a selected illumination level different from the illumination rating or a selected color temperature different from the color temperature rating, and supplying illuminating light of an illumination level and a substantially constant color temperature based upon the selected threshold parameter.
In still another advantageous embodiment a portable endoscopic imaging system is provided comprising a battery, providing electrical power, and a power conditioning circuit, conditioning the electrical power and having a voltage regulator, for maintaining a selected output voltage level. The apparatus further comprises a light source, having a selected illumination level and a selected color temperature, for providing illuminating light of a selected color temperature, and a portable imaging device, for viewing the image of an object illuminated by the illuminating light. In addition, the power conditioning circuit provides a substantially constant output voltage level based upon a selected threshold parameter and said light source provides a substantially constant illumination level and a substantially constant light color temperature based upon a selected threshold parameter.
In yet another advantageous embodiment a portable imaging system comprising a portable power source, a light source, having a selected illumination level and a selected color temperature, and a power conditioning circuit, that provides a constant voltage level based upon a selected threshold parameter. Furthermore, the light source is re-rated to provide a substantially constant illumination level and a substantially constant light color temperature that is higher than the selected illumination level and a color rating that is shifted toward ultra-violet from the selected color temperature.
The invention and its particular features and advantages will become more apparent from the following detailed description considered with reference to the accompanying drawings.